When I turn my Windows XP Professional PC on it goes past the Windows XP loading screen then I get blue screen of death with the error C000021a the session manager initialization system process terminated unexpectedly with a status of 0xc000003a I have no idea what the error means or how to fix it any help would be appreciated

I have tried to boot off Windows XP and recovery mody chkdsk /r but this didn't fix it

A. Connect your non-bootable hard drive to another computer, as a secondary drive or use a usb adapter or enclosure, If you can see your data on the drive, back it up Now, then follow the rest of these instructions.

NOTE
D: may not represent the hard drive you connected to your PC, it may be E: or F: or G:, it all depends on how many other drives (including cd/dvd) you have in your host PC, So substitute the appropriate drive letter in the instructions below.

C. Navigate to the D:\System Volume Information folder. You will see a folder named something like _restore{.........} the dots represent an alpha-numeric sequence.

In this folder you will see folders named RP0....RPnn. Find the one with the highest number.

These are your System Restore points. In the highest numbered folder you will see a folder named snapshot. In this folder are registry hive files which you need to recover your system:

_registry_user_.default

_registry_machine_security

_registry_machine_software

_registry_machine_system

_registry_machine_sam

D. Create a subdirectory; i.e, D:\Windows\TMP. Copy these files to the TMP subdirectory. Rename them to:

default

SECURITY

software

system

SAM

Note Be sure to lose the period (.) in the file named _registry_user_.default

E. Delete the files in the D:\windows\system32\config subdirectory with the same short names.

F. Copy the D:\windows\tmp files to the D:\windows\system32\config. subdirectory.

G.Put your drive back in its original system. Your system should start normally. If you get the same error repeat the procedure and choose another folder ( RPnn) (next highest number). You can repeat this procedure choosing lower RPnn numbers until you get it booting again.